Internal combustion engine arrangement



Oct. 26, 1943. w. E. JOHNSON 3 9 INTERNAL COMBUSTION ENGINE ARRANGEMENT Filed Aug. 26, 1942 lhvehtor-z WIFrfiid E. Johnson, fi an 7 am/ 1 His Attorney.

(the speed within i'airly narrow limits. l speed which' first action, however, is air flows' at 'sound P tenta& Oct. 2671943' oF -cE I Wiltrid E. Johnson, Ma'rblelead, Masa., assignor N to General Electric Company, a corporation of j V New York Application August 26, 1343, Serial No. 456,l76

L 6 Claims; '(c. 12343) The present invention relates to internal comr bustion engine arrangements and is of particular interest in connection with two-cycle internal combustion engines although it is not necessarily limited thereto. In certain cases where the load requirement of-an internal combustion engine is substantially constant or varies within a small range; for example 'a range of the order of per cent, it has heretofore been the practice to provide complicated and 'expensive engine control mechanisms to vary the supply of Operating medium to the engine in response to speed changes of the 'engines or other indications of load varia- ;tion in order to maintain the speedjsubstantially constant. i

One object of my invention is to provide an proved combustion engine arrangement in which the speed of a combustion engine is maintained within a narrow range for a given load output without the provision of a particular speed-goveming mechanism. This is accom- ;plished in accordance with my invention by the provision of means or. conducting Operating medium such as a'mixture of fuel and air to the engine, which means includes a: venturi tube designed to cause the medium flowing therethrough to attain sonic velocity at the required engine load output. Thus, it an engine according to my invention is required to furnish a load output of 100 I provide the engine with a venturi for conducting air and fuel to -an inlet chamber of the engine, which venturi is designed to produce sound velocity of the air flowing therethrough at the required load output of 100 kw. The sonic velocity of the medium flowing through the neck of the venturi constitutes a deflnite limitation of the weight-flow per minute nary engines of this type are operated, a change in engine speed causes a change in pressure in the inlet chamber and consequently a change in pressure drop and as a result thereof a change in flow. With my invention as pointed out above the flow 'will remain constant because the change in pressure drop does not aifect the flow at sonic velocity in the venturi.

In the accompanying drawing I have' shown in F'g. 1 a diagrammatic viewof an embodiment of my invention, and in l ig. 2 a modification i of a part of Fig; 1.

'Ihe arrangement of Fig.- 1` compris es 'a twocycle internal combustion engine lil having a crank shaft ll arranged to drive a machine Iz which 'may be a pum a generator, or the like normally requiring a substantially constant load input. The two-cycle combustion engine lil has a cranl casing 3 which also* constitutes a compression chamber I 3. An upper portion of the c'asing l3 is integrally united with a cylinder |4 having a detachable cover |5 with a spari: plug s. A piston |1 movably disposed in the cylinder His connected by a rod I 8 to the crank shaft ll`. The cylinder ll has an inlet port lil'communicating with the crank casing or compression chamber 13 for receiving a mixture ot fue] and ar, and an outlet or exhaust port 20 for discharging bumed gases from the cylinder to atmosphere. Fuel and air are supplied to the enine by means including a venturi 2| having an' inlet opening 22 ,for receiving air and an outlet' projecting into a' receiving chamber 23 formed of air through the venturi. Once sonic velocity is reached in the venturi a' further increase of the flow therethrough becomes impossible, irrespective of changes in engine speed which may occur. Thus, once sonic velocity is attained in the venturi, a change in speed will only aflect the charge of air and fuel delivered to an engine cylinder per stroke. The amount of fuel and air per stroke then will decrease with increasing engine speed and,*vice versa,` the charge per stroke will increase with decreasing engine speed. The variation of the charge per stroke upon changes of speed of the engine acts to control If at a produces sonic velocity in the venturi the'englne torque is 10 per cent in excess oi' that required, the speed of the enginewill increase 10 per cent, causing a corresponding decrease in'torque to balance the load. This posslbleonly as long as, the velocity through the narrow portion oi' ..the-venturi. At velocities below 'that of sound in the venturi, at which velocities ordi- `'to my' invention is designed to' cause the air by the engine casing 'and communicating with the compression-chamber |3 through nonreturn valve 24. Fuel is conducted to the venturi 2l by a pipe 25 connected to a port 26 in the venturi at a point beyond the throat of the venturi as regards the' direction of flow therethrough.

During operation the fuel and the air passed through the venturi are mixed in the chamber 23 and from there drawn into the compression chamber. |3 during the upward stroke of the piston l'l. Downward movementiof the piston ll causes compression of the mixture .in the 'chamber beyond the port IS the compressed mixture ot I3-and as the piston l' moves down air and fuel is forced through the port IS into the cylinder to be bumed therein and after ex-e` pansion to be discharged through "the outlet port 20. 'As explained above, the venturi ZI according supplied therethro'gh to attain sonic velocity at the required load output of the engine. With suchan .arrangement the engine becomes selfcontrolling without the provision of particular' 4 governing mechanisms because a change in speed d e to a variation in load causing a change in inlet pressure in the chamber 23 does not aflect the. flow throughthe venturi2l. The weig tflow -per minute of air conductedthrogh 'the ventu-ri remains suhstantially constant.

If it is desired to operate an engine according to myinvention fat diflerent load outputs and to keep the speed for each particular output within narrow limits, this' may be readily accomplished' by thexprovision of means to control the effective In the present throat area of the venturi 2l example I have shown a needle valve member 21. pro'jecting into the throat of the venturi 21 and pivotallyconnected to one end of a fulcrum lever '23, the'other end 'of'which is pivotally connected ,to a control lever 23. 'According to my invention upon change in load requirement from the engine o the valve 21 is positioned in the venturi throat until the air-flow therethrough attains sonic velocity at the required engine load output. Thus, if only half of the normal load is required from the engine o the needle valve 21 is moved into the throat to reduce the effective throat area until the' air-flow therethrough reaches sonic velocity at`h alf engine load output. Thus, my invention comprises a new method of Operating and controlling internal combustion engines subject to varyi''g loaddemandaccording to w h the effective *throat area of a nozzle such as Venturi tube is varied upon changes in loadl de-',

mand to maintain the velocity of the medium at sound velocity in the throat area for each load. As a result of such operation the speed of the engine is automatically held within a comparatively narrow range of say about 10 per cent without re'quiring the provision of a` special speedcontrolling mechanism.

- Fig. 2 'shows another arrangement for varying the flow to a rception chamber to satisfy difier- 'ent load requirements. The arrangement inv cludes an inIet chamber 30 corresponding to the. chamber 23 of Fig: 1 and a plurality ot ventu-is 3I, 32 connected thereto. The ii'ow through the venturis may b'econtrolled by movable valve l possible loads flxed by' the throat area or the small venturi :I .and the total ,threat area r of' both venturis :I and 32respectively.

What Iclaim anew and desire to secure by Letters Patent of the United States is: 4

1. In an internal combustion engine a Venturi tube !or eonducting Operating medium thereto, the tubebeing designed with athroat area in which the Operating medium attains' .sound velocity at the normal load' output o! the engine in order to maintain the engine speed range within narrow limits upon slight variations otthe load output in the absence of. a speed goveming agency. v

2. In an internal combustion engine a co us tion chamber, and the combination of a Venturi tube forconducting eombustion *air thereto, said tube having an eflective throat area dimension ed to cause the normal air-flow therethrough to attain sound velocity at the required load output of the engine automatically to limit the speed range upon variations in load and to permit operation of the engine without a special load and speed governing device.- v c 3. -In a two-cycle combustion engine the combination of a chamber for receiving a mixture of V fuel and air, and means for conducting air to 1 to causewthe air-flow therethrough to attain sonic members 33 and 34 'respectively, pivotally coni nected to a lever 35 on -opposite sides from a fulcrum 33 for supporting the lever 35 on a wall. Turningmolement ofthe lever 35 in'clockwise direction about the fulcrum 36 causes opening of' nected in parallel to' the chamber, said ventn'is the 'small venturi 3| and closing of the larger;

venturi 32 and vice versa. During low load requirements the engne is operated by means of the venturi 3| and during high load requiremnts the engine is operated by the larger venturi 32 or by both venturis 3| and 32. In the position show'nthe valve members 33, 34 are both in suhstantially `fully open position, permitting ma imum load output ot the engine as determined by the maxim'um flow through both venturis 3 32 at sound velocity. Upon decreased loadrequiremeisit` the' lever 35 may be turned c`ountr-. clockwise until in an end'position the venturi :i: is completely closed in which portion the load output is limited by the maximum flow 'through the larger venturi 32. 'II the load demand'should drop further, the lever 35 w`ill he turned clock wise to open the ventui and to reduce the e'ifee tive area :through theiventuri 32 until 'in an end 4 position "the ventu'ri 32 is completely closed and the flow is reduced to a minimum by the -verturi 3l. With this arrangemen t the engine may be `controlled tohold any loadl within a relatively h narrow speed range, between the and the chamber including a venturi having a threat area dimensioned to cause the air-flow therethrough to attain sound velocity at the maximum load output required from the engine in ordr to prevent increase in flow through the venturi upon decrease in load demand, and means for varying the effective threat area of the venturi velocity upon decrease in load demand from the engine. I

' 4. In an internal combustion enginethe combination of a chamber for receiving a mixture of uel and air,`and` means for eonducting air to the chmber including a plurality of venturis conhaving a total throatarea dimensioned to cause the air-flow thereth'rough to attain sound velocity for a maximum load output requirement of' the engine.

5. In an internal combustion' engine the com bination of achamber for receiving a' mixture of uel and air, and means for conducting air to the chamber including a plurality of venturis con nected in pafalle to the chamber, said venturis having. a total throatarea dimensioned to 'cause the air-flow therethrough to attainsound velocits for a maximum load output requirement of the "engine, 'and mean'sto vary the effective throat area of at least'on'e of the venturissto perinit operation oi the engine under varyingdoad'requirements at sound velocity 'of the operating medium through the venturis 'for each particulaload requirement. i

6. The method of Operating an bu'stion engine having a combustiouchamber and vntur means with an `^adjustable threat area through which 'air is supplied to the' chamber,

which' method comprises adjusting the throat area to maintain air-flow therethrough at. sonic velocity upon changes of load demand from the engine; e u JOHNSON.

'for operation at loads varying within a small range only, I a combustion chamber, and the combination of internal con 

